U.S. patent application number 17/463567 was filed with the patent office on 2022-03-03 for heat transferring device and method for making thereof.
The applicant listed for this patent is City University of Hong Kong. Invention is credited to Mengnan JIANG, Yang WANG, Zuankai WANG.
Application Number | 20220065552 17/463567 |
Document ID | / |
Family ID | 1000005865544 |
Filed Date | 2022-03-03 |
United States Patent
Application |
20220065552 |
Kind Code |
A1 |
WANG; Zuankai ; et
al. |
March 3, 2022 |
HEAT TRANSFERRING DEVICE AND METHOD FOR MAKING THEREOF
Abstract
The present invention provides a heat transferring device and a
method for making thereof. The heat transferring device has a
thermal conducting substrate and a porous layer. The thermal
conducting substrate has a plurality of protrusions and concave
bottom surfaces. The concave bottom surfaces are located between
the protrusions. The porous layer is embedded between the
protrusions. The present invention also provides a high temperature
material transferring system comprising a cylindrical container and
the heat transferring device disposed on the surface of the
cylindrical container.
Inventors: |
WANG; Zuankai; (Hong Kong,
HK) ; JIANG; Mengnan; (Hong Kong, HK) ; WANG;
Yang; (Hong Kong, HK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
City University of Hong Kong |
Hong Kong |
|
HK |
|
|
Family ID: |
1000005865544 |
Appl. No.: |
17/463567 |
Filed: |
September 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63072995 |
Sep 1, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 17/02 20130101 |
International
Class: |
F28D 17/02 20060101
F28D017/02 |
Claims
1. A heat transferring device, including: a thermal conducting
substrate having a plurality of protrusions and concave bottom
surfaces, wherein the concave bottom surfaces are located between
the protrusions; and a porous layer embedded between the
protrusions.
2. The heat transferring device of claim 1, wherein the porous
layer is suspended above the concave bottom surfaces, creating gap
spaces between a bottom side of the porous layer and the concave
bottom surfaces.
3. The heat transferring device of claim 1, wherein the porous
layer makes contact with the concave bottom surfaces.
4. The heat transferring device of claim 1, wherein a material of
the protrusions has high thermal conductivity.
5. The heat transferring device of claim 1, wherein the concave
bottom surfaces form a plurality of first grooves and second
grooves, and the first grooves intersect the second grooves.
6. The heat transferring device of claim 5, wherein the first and
second grooves have U-shaped profile.
7. The heat transferring device of claim 1, wherein the protrusions
form an array.
8. The heat transferring device of claim 1, wherein circumference
of each of the protrusions increases in a direction towards its
bottom.
9. The heat transferring device of claim 1, wherein a material of
the porous layer is inorganic.
10. The heat transferring device of claim 1, wherein a material of
the porous layer has a thermal conductivity that is N times smaller
than a thermal conductivity of a material of the protrusions, and
the N is a number within a range from 100 to 1,000.
11. The heat transferring device of claim 1, wherein the porous
layer is fabricated via electrospinning technique.
12. The heat transferring device of claim 1, wherein the porous
layer has a plurality of nanofibers, and the nanofibers are
interweaved together.
13. The heat transferring device of claim 1, wherein the porous
layer is made of thermally insulating material.
14. A method of forming a heat transferring device, comprising:
providing a thermal conducting substrate; forming a plurality of
protrusions and concave bottom surfaces, wherein the concave bottom
surfaces are located between the protrusions; and embedding a
porous layer between the protrusions.
15. The method of claim 14, wherein the step of forming the
protrusions comprises: wire-cutting the thermal conducting
substrate with a Molybdenum wire or micro-milling the thermal
conducting substrate.
16. The method of claim 14, wherein the porous layer is fabricated
via electrospinning technique.
17. The method of claim 14 further comprising: sintering the
protrusions and the porous layer.
18. A high temperature material transferring system, comprising: a
cylindrical container; and the heat transferring device of claim 1
disposed on the surface of the cylindrical container.
19. The high temperature material transferring system of claim 18
further comprising a plurality of blades disposed in the
cylindrical container.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Utility
Patent Application No. 63/072,995 filed Sep. 1, 2020; the
disclosure of which is incorporated herein by reference in its
entirety.
COPYRIGHT NOTICE
[0002] A portion of the disclosure of this patent document contains
material, which is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
TECHNICAL FIELD
[0003] The present invention relates generally to techniques and
mechanisms for transferring thermal energy. More particularly, the
present invention relates to phase change heat transfers.
BACKGROUND
[0004] A stable, controllable, and highly efficient phase change
heat transfer is crucial for many high temperature applications in
consumer, commercial, industrial, and research facilities and
products, such as quenching, fire-extinguishing, cooling for power
plants, smelting plants, refinery, computer data centers,
combustion engines, jet engines, and explosion chambers. Many
strategies have been proposed to enhance phase change heat transfer
on high temperature surface.
[0005] However, on a high temperature surface (i.e., above
300.degree. C.), one of the bottlenecks of enhancing phase change
transfer performance is the Leidenfrost effect. The Leidenfrost
effect is a physical phenomenon in which liquid, when placed close
to a surface that is significantly hotter than the liquid's boiling
point, produces an insulating vapor layer that keeps the liquid
from boiling rapidly. Because of this "repulsive force", droplets
hover over the surface rather than making physical contact with the
hot surface. The thermal insulating vapor layer prevents
liquid-solid contact and severely deteriorates the heat transfer
performance.
SUMMARY OF THE INVENTION
[0006] It is an objective of the present invent to provide a novel
and general architecture that can suppress the Leidenfrost effect
even on surfaces with ultrahigh temperature up to the melting point
of the material used in the architecture, while without
compromising the heat transfer in the entire temperature range.
Under the various embodiments of the present invention, when a
liquid droplet (i.e., of .about.170 .mu.L in volume) impacts on the
architecture with a broad temperature, for example, ranging from
100.degree. C. to 1,200.degree. C., the droplet always exhibits
rapid spreading, intense boiling, and rare splashing instead of
creating the insulating vapor layer. As such, the droplet's
evaporation times are almost constant, giving a characteristic
timescale of less than 1 s under a wide temperature range of
200-1,200.degree. C., in contrast to several tens of seconds on
flat surface when temperature is higher than -200.degree. C. owing
to Leidenfrost effect.
[0007] The present invention provides a heat transferring device
and a high temperature material transferring system. The heat
transferring device has a thermal conducting substrate and a porous
layer. The thermal conducting substrate has a plurality of
protrusions and curved (or concave) bottom surfaces. The concave
bottom surfaces are located between the protrusions. The porous
layer is embedded between the protrusions.
[0008] The high temperature material transferring system includes a
cylindrical container and the heat transferring device. The heat
transferring device is disposed on the surface of the cylindrical
container.
[0009] The present invention also provides a method of forming a
heat transferring device. The method includes providing a thermal
conducting substrate; forming a plurality of protrusions and
concave bottom surfaces between the protrusions; and embedding a
porous layer between the protrusions.
[0010] In an embodiment of the present invention, the placement of
porous layer is suspended from the concave bottom surfaces,
creating gap spaces in between the bottom side of porous layer and
the concave bottom surfaces; the material of the protrusions has a
high thermal conductivity; the concave bottom surfaces form a
plurality of first grooves and second grooves; the first grooves
intersect the second grooves; the first and second grooves have a
U-shape profile; the protrusions form an array; the circumference
of each of the protrusions increases in a direction towards its
bottom, forming a pyramid or frustum; the material of the porous
layer is inorganic; the material of the porous layer has a thermal
conductivity that is N times smaller than a thermal conductivity of
a material of the protrusions, and N is within a range from 100 to
1,000; the porous layer is made of thermally insulating material;
and the step of forming the protrusions comprises: wire-cutting the
thermal conducting substrate with a Molybdenum wire, or
micro-milling the thermal conducting substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Embodiments of the invention are described in more details
hereinafter with reference to the drawings, in which:
[0012] FIG. 1 depicts a perspective view of a heat transferring
device in accordance with one embodiment of the present
invention;
[0013] FIG. 2 depicts another perspective view of a heat
transferring device in accordance with one embodiment of the
present invention;
[0014] FIG. 3 depicts a top view of the thermal conducting
substrate in accordance with one embodiment;
[0015] FIG. 4 depicts a side sectional view of the heat
transferring device taken along a cutting plane line S1 in FIG.
1;
[0016] FIG. 5 depicts a side sectional view of the heat
transferring device in accordance with another embodiment;
[0017] FIG. 6 depicts a side sectional view of the heat
transferring device in accordance with another embodiment;
[0018] FIG. 7 depicts a side sectional view of the heat
transferring device in accordance with another embodiment;
[0019] FIG. 8 depicts a side sectional view of the heat
transferring device in accordance with another embodiment;
[0020] FIG. 9 depicts a top view of the thermal conducting
substrate in accordance with another embodiment;
[0021] FIG. 10 depicts a top of the thermal conducting substrate in
accordance with another embodiment; and
[0022] FIG. 11 depicts a schematic drawing of a high temperature
material transferring system in accordance with one embodiment.
DETAILED DESCRIPTION
[0023] In the following description, devices for facilitating heat
transfer and methods for making thereof and the likes are set forth
as preferred examples. It will be apparent to those skilled in the
art that modifications, including additions and/or substitutions
may be made without departing from the scope and spirit of the
invention. Specific details may be omitted so as not to obscure the
invention; however, the disclosure is written to enable one skilled
in the art to practice the teachings herein without undue
experimentation.
[0024] FIG. 1 and FIG. 2 show the perspective views of a heat
transferring device 1A in accordance with an embodiment of the
present invention. The heat transferring device 1A has a thermal
conducting substrate 11 and a porous layer 12.
[0025] The thermal conducting substrate 11 has a plurality of
protrusions 111 and concave bottom 112. In this embodiment, the
protrusions 111 and the curved (or concave) bottom surfaces 112 are
formed on the same side of the thermal conducting substrate 11. The
concave bottom surfaces 112 are located between the protrusions
111. In other words, between any of the protrusions 111 and the
other adjacent protrusion 111, a concave bottom surface 112 is
formed between the bottoms of two protrusions 111.
[0026] The porous layer 12 is embedded between the protrusions 111.
In this embodiment, the protrusions 111 stab or poke through the
porous layer 12, and the porous layer 12 is secured to the thermal
conducting substrate 11 by the protrusions 111.
[0027] In this embodiment, when water droplet 2 impacts on the
porous layer 12 of the heat transferring device 1A with a broad
temperature range from approximately 100 to 1,200.degree. C., the
droplet always exhibits rapid spreading, intense boiling, and rare
splashing instead of Leidenfrost phenomenon. In other words, the
water droplet 2 smears in the porous layer 12, and, when the heat
transferring device 1A is attached on surface 31 of cylindrical
container 3 (only part of the layer and outer surface of the
cylindrical container 3 is shown in the figure), the thermal
conducting substrate 11 absorbs the heat H1 from the cylindrical
container 3, and the smeared area 121 further absorbs the heat H2
without forming an insulating vapor layer.
[0028] Also, protrusions 111 of the thermal conducting substrate 11
may act as a "thermal bridge" to "short circuit" the thermal flow
directly from the thermal conducting substrate 11 to the liquid in
the porous layer 12. Meanwhile, the porous layer 12 is made of
thermally insulating material, and the porous layer 12 with
sufficient capillary force wicks and spreads the liquid, further
improving the efficiency of heat dissipation.
[0029] More specifically, the bottom side, which is opposite to the
side having the protrusions 111, of the thermal conducting
substrate 11 may contact a high-temperature material transferring
system (i.e., the cylindrical container 3). The high-temperature
material transferring system may be, without limitation, a power
generator or reactor and piping thereof, a smelter, an explosion
chamber, an engine cooling system, or a computer cooling system.
When the thermal conducting substrate 11 absorbs the heat from the
device, the heat may be transfer to the liquid in the porous layer
12 effectively. After the liquid, such as water, changes its phase
to gas phase, heat from the high-temperature device is
dissipated.
[0030] Together, the synergistic cooperation between the
protrusions 111 and the porous layer 12 achieve the dramatic boost
in the Leidenfrost temperature point without sacrificing its heat
transfer performances, resolving the conflicting requirement on
heat transfer and wickability.
[0031] The material of the thermal conducting substrate 11 has high
thermal conductivity. That is, the material of the protrusions has
high thermal conductivity. In one embodiment, the thermal
conducting substrate 11 is made of steel, a good thermal conductor
with the thermal conductivity of .about.25 Wm.sup.-1K.sup.-1. In
other embodiments, the material of the thermal conducting substrate
11 may be iron-based, nickel based, cobalt-based, zirconium-based,
titanium-based material, or tungsten, rhenium, molybdenum, niobium,
or metal ceramic material, or silicon nitride, carbon nitride,
tantalum carbide, or hafnium carbide.
[0032] A material of the porous layer 12 is inorganic. For example,
the material may be silicon dioxide. To be specific, the porous
layer 12 may be fabricated via electrospinning technique, and the
porous layer 12 is composed of SiO.sub.2 composite, which endows
the layer 12 with flexibility and high-temperature tolerance of up
to, for example, .about.1,200.degree. C., which is the melting
point of the SiO.sub.2 composite. The porous layer 12 comprises
nanofibers and these nanofibers interweave together, forming
inter-fiber pores with an average diameter of .about.2 m and
leading to the high porosity of the layer 12 (.about.0.95).
Moreover, large roughness generated by the fibrous structure makes
the hydrophilic layer with an intrinsic contact angle of .about.30
degree to be super-hydrophilic.
[0033] In this embodiment, the thermal conductivity of the material
of the porous layer 12 is about 0.02 Wm.sup.-1K.sup.-1, which is
about 1,000 times smaller than that of the material of the thermal
conducting substrate 11. To be more specific, the porous layer 12
is made of thermally insulating material. Thus, the protrusions 111
of the thermal conducting substrate 11 act as a "thermal bridge" to
"short circuit" the thermal flow directly from high temperature
thermal conductive substrate 11 to the droplet 2.
[0034] In various embodiments, the porous layer 12 may be made of
carbon fibers, aramid fibers, glass fibers, basalt fibers,
polybenzimidazole (PBI) fibers, or
ultra-high-molecular-weight-polyethylene (UHMWPE). In other
embodiments, the porous layer 12 may include one or more of porous
film made of fiber, ceramic, and metal. In some other embodiments,
the material of the porous layer 12 may include one or more of
silicon dioxide, titanium dioxide, mullite, aluminum oxide,
zirconium dioxide, yttrium oxide, and asbestos. In still some other
embodiments, the porous layer 12 is of felt or aerogel. In some
embodiments, the thermal conductivity of the material of the porous
layer 12 is about N times smaller than that of the material of the
thermal conducting substrate 11, and N is within a range from 100
to 1,000.
[0035] FIG. 3 is a top view of the thermal conducting substrate 11
of an embodiment. In this embodiment, the protrusions 111 form an
array, and the concave bottom surfaces 112 form a plurality of
grooves 113 and grooves 114; and the grooves 113 intersect the
grooves 114.
[0036] More specifically, the grooves 113 extend along the axis X1,
X2, and X3 respectively, and the axis X1, X2, and X3 are parallel
to direction d1. The grooves 114 extend along the axis Y1, Y2, and
Y3 respectively, and the axis Y1, Y2, and Y3 are parallel to
direction d2. The direction d1 is perpendicular to the direction
d2, and the grooves 113 intersect the grooves 114.
[0037] FIG. 4 is a side sectional view of the heat transferring
device 1A taken along a cutting plane line S1 in FIG. 1. The bottom
side of the porous layer 12 keeps a gap g1 from each of the concave
bottom surface 112. Vapor channels are formed between the concave
bottom surfaces 112 and the bottom surface 122 of the porous layer
12.
[0038] In this embodiment, the grooves 113, 114 have U-shape
profile, and a sufficient tunnel is provided for vapor exhausting.
The vapor channels can prevent the water droplet from bouncing away
from the porous layer 12. In other words, the "U" shaped grooves
113, 114 between the porous layer 12 and the thermal conducting
substrate 11 are used for exhausting vapor. Therefore, liquid may
stay in the porous layer 12 and absorbs heat from the protrusions
111 of the thermal conducting substrate 11.
[0039] Moreover, the circumference of each of the protrusions 111
increases towards its bottom. In this embodiment, width r1 of the
protrusion 111 near its top is smaller than width r2 of the
protrusion 111 near its bottom. The "U" shaped groove 113 forms a
fillet (i.e., the concave bottom surface 112) at valley in between
the protrusions 111. These increasing circumferences of the
protrusions 111 towards their bottoms prevent the porous layer 12
from moving downward by the pushing force exerted on it during the
droplets' impact.
[0040] For example, the fillet radius r3 is approximately
0.15.+-.0.02 mm, and the width w, spacing g2, and height h of
protrusions 111 are approximately 300 .mu.m, 300 .mu.m, and 400
.mu.m, respectively. The density of protrusions 111 is high enough
to transfer the heat, and the grooves 113, 114 are wide enough for
water droplet to spread and smear on the porous layer 12.
[0041] For another example, the fillet radius r3 is approximately
1.0.+-.0.02 mm, and the width w, spacing g2, and height h of
protrusions are approximately 2.0 mm, 2.0 mm, and 4.0 mm,
respectively, and the heat transferring device 1A can applied to
quenching, fire-extinguishing, cooling for power plants, smelting
plants, combustion engines, jet engines, and explosion chambers. In
other words, the fillet radius r3 may be within a range from 0.13
mm to 1.0 mm, and the width w may be within a range from 300 .mu.m
to 3000 .mu.m, and the spacing g2 may be within the range from 300
.mu.m to 3000 .mu.m, and the height h may be within the range from
400 .mu.m to 4000 .mu.m.
[0042] The porous layer 12 has a thickness t1, and the porous layer
12 provides 3-dimensional channels. The 3-dimensional channels
provide a fast radial and vertical wicking during a droplet
contact, and the channels dramatically enhances liquid spreading
area and heat transfer performance. In other words, the porous
layer includes a plurality of 3-dimensional channels.
[0043] Also, the thickness t1 of the porous layer 12 is less than a
height h of every protrusion 111, and the circumference of each of
the protrusions 111 increases in a direction towards its bottom,
forming a pyramid or frustum, such that the protrusions 111 can
hold and suspend the porous layer 12 above the concave bottom
surfaces 112, creating the gap spaces g1 between the bottom side of
the porous layer and the concave bottom surfaces 112.
[0044] In one embodiment, the protrusions 111 take the shape of a
square-based frustum as shown in the figures. In other embodiments,
the protrusions 111 may take the shape of circle, elliptical, or
different polygonal-based frustum or pyramid.
[0045] FIG. 5 is a side sectional view of a heat transferring
device 1B. In some embodiment, the porous layer 12 contacts concave
bottom surfaces 112. The heat transferring device 1B has a thermal
conducting substrate 11 and porous layer 12, and the porous layer
12 filled the bottom of the grooves 113 of the thermal conducting
substrate 11.
[0046] FIG. 6 is a side sectional view of a heat transferring
device 1C. In some embodiments, the bottom surface 112 may form a
series of steps. The stair shaped groove 113 forms the concave
bottom surface 112 at valley in between the protrusions 111. The
steps may hold the porous layer 12 at a precise height.
[0047] FIG. 7 is a side sectional view of a heat transferring
device 1D. In some embodiments, the bottom surface 112 may form a
series of teeth. The comb shaped groove 113 forms the concave
bottom surface 112 at valley in between the protrusions 111. The
teeth may improve the efficiency of heat dissipation.
[0048] FIG. 8 is a side sectional view of a heat transferring
device 1E. In some embodiments, the bottom surface 112 may have
microstructures. The rough shaped groove 113 forms the concave
bottom surface 112 at valley in between the protrusions 111. The
microstructures may improve the efficiency of heat dissipation as
well.
[0049] FIG. 9 is a top view of a thermal conducting substrate 11A.
In some embodiments, top surfaces of the protrusions 111 are
triangular. In this case, the thermal conducting substrate 11A may
be applied to a triangular area more properly.
[0050] FIG. 10 is a top view of a thermal conducting substrate 11B.
In some embodiment, top surfaces of the protrusions 111 are
hexagonal. In this case, the thermal conducting substrate 11B may
be applied to a hexagonal area more properly.
[0051] A skilled person in the art would appreciate that top
surfaces of the protrusions 111 may readily adopt other shapes
without undue experimentation or deviation from the spirit and
purpose of the present invention.
[0052] FIG. 11 is a schematic view of a high temperature material
transferring system 3. The system 3 has a cylindrical container 31,
and the cylindrical container 31 is configured to transfer air flow
having high temperature in high speed. The heat transferring device
1A is disposed on the surface of the cylindrical container 31.
Therefore, the system 3 can be cooled down with water spray
easily.
[0053] In one exemplary embodiment, system 3 is an aero engine, and
the system 3 further includes a plurality of blades 32. The blades
32 are disposed in the cylindrical container 31, and the heat
transferring device 1A is also disposed on the surface of the
blades 32. Therefore, the blades 32 may also be cooled down quickly
with water spray.
[0054] In other embodiments, container 31 may take other shapes,
and the heat transferring device 1A is disposed on the surface of
the container 31. A skilled person in the art would appreciate that
embodiments of the present invention with the heat transferring
device 1A being flexible can have many different applications; for
example, container 31 may be part of a flexible thermal dissipation
armor.
[0055] In some embodiments, the heat transferring device 1A can be
provided as a film, which can apply on the surfaces of a
high-temperature material transferring system such as a power
generator or reactor and piping thereof, a smelter, an explosion
chamber, an engine cooling system, or a computer cooling system. In
some embodiments, the heat transferring device 1A can be provided
as small units, which can be mixed with liquid, such as water, to
obtain a higher cooling rate suitable for use as fire extinguisher
in addition to the high-temperature material transferring systems
above.
[0056] In other embodiments, the thermal conducting substrate 11
may have a thickness within the range from 0.1 to 0.5 mm, and the
heat transferring device 1A can be brazed or bonded to various
surfaces or materials with different shapes which is hard to
texture directly.
[0057] Referring to FIG. 1. The present invention also provides a
method of forming the heat transferring device 1A. The method
includes: providing a thermal conducting substrate 11; and forming
a plurality of protrusions 111 and concave bottom surfaces 112.
[0058] In this embodiment, the thermal conducting substrate 11 is
made of steel, and the protrusions 111 arrays are fabricated using
wire-cutting machine. To be more specific, the wire-cutting process
used Molybdenum wire with diameter of 0.18 mm to form the "U" shape
groove.
[0059] In one embodiment, the thermal conducting substrate 11 and
the protrusions 111 thereon are fabricated using molding, and the
mold is fabricated by 3D printing. In some embodiment, the thermal
conducting substrate 11 is made directly by 3D printing. In another
embodiment, the thermal conducting substrate 11 is made by
micro-milling.
[0060] The method of forming the heat transferring device 1A
further includes embedding a porous layer 12 between the
protrusions 111. In this embodiment, the porous layer 12 is
fabricated via electrospinning technique.
[0061] The porous layer 12 is made of thermally insulating
composite fibers. Typically, the PVA (polyvinyl alcohol) precursor
solution (10 wt. %) was prepared by dissolving PVA (Mw=88,000
gmol.sup.-1) into deionized water at 80.degree. C. with continuous
stirring for 12 h. Then the silane sol was obtained by stirring the
TEOS (tetraethoxysilane) aqueous solution with H.sub.3PO.sub.4 as
hydrolysis catalyst at room temperature for 10 h, and the molar
ratio of TEOS:H.sub.3PO.sub.4:H.sub.2O=1:0.01:10. Subsequently, 12
g silane sol was dripped to the PVA precursor solution of equal
weight and stirred for another 4 h till a homogenous solution was
obtained. The electrospinning was performed under an applied
voltage of 18 kV, and the precursor solution was injected at a flow
rate of 1 mlh.sup.-1. An aluminum foil-covered grounded metallic
rotating roller was used as a collector. The as-spun composite
fibers were dried at 80.degree. C. for 2 h and then calcined at
800.degree. C. in air for 2 h to remove the organics.
[0062] The embedding is using a reverse mold of the thermal
conducting substrate 11. By using PDMS as material of the reverse
mold, the porous layer 12 is pressed and embedded between the
protrusions.
[0063] In order to further compacting and forming the heat
transferring device 1A, the thermal conducting substrate 11 and the
porous layer 12, which is embedded into the array with specific
depth, are sintered at a temperature of 800.degree. C. Therefore,
the porous layer 12 and the thermal conducting substrate 11 is
combined with good thermal conducting function.
[0064] The foregoing description of the present invention has been
provided for the purposes of illustration and description. It is
not intended to be exhaustive or to limit the invention to the
precise forms disclosed. Many modifications and variations will be
apparent to the practitioner skilled in the art.
[0065] The embodiments were chosen and described in order to best
explain the principles of the invention and its practical
application, thereby enabling others skilled in the art to
understand the invention for various embodiments and with various
modifications that are suited to the particular use
contemplated.
[0066] Moreover, in interpreting the invention, all terms should be
interpreted in the broadest possible manner consistent with the
context. In particular, the terms "includes", "including",
"comprises" and "comprising" should be interpreted as referring to
elements, components, or steps in a non-exclusive manner,
indicating that the referenced elements, components, or steps may
be present, or utilized, or combined with other elements,
components, or steps that are not expressly referenced.
* * * * *